This invention relates to a vibration damping supporting strut for a motor vehicle for absorbing vehicle body natural frequency vibrations.
Shock absorber struts are known in the case of vehicles which, for the absorbing of natural torsional frequencies of the vehicle body have an absorber mass on the piston rod in the area of its support on the vehicle body. Because of the required space in this area, this arrangement presents problems, and furthermore, an absorber mass which is arranged in this manner is subjected to exterior influences.
It is an object of the invention to develop a supporting strut for a motor vehicle in such a manner that, while an additional space requirement is avoided, an effective absorbing of natural torsional frequencies of the vehicle body is ensured.
According to the invention, this object is achieved providing a strut arrangement disposable between a motor vehicle body and a wheel suspension element for absorbing natural frequencies of a vehicle body, said strut arrangement comprising:
a piston rod held in an elastic bearing at a vehicle body part, said piston rod including a longitudinally extending hollow space therein,
an absorber mass disposed in the hollow space to be axially movable therein with first and second clearance spaces at respective opposite ends of the absorber mass,
a first spring element disposed in the first clearance space and supporting the absorber mass,
a second spring element disposed in the second clearance space and supporting the absorber mass,
a fluid medium filling the first and second clearance spaces, and
a fluid connection between the first and second clearance spaces.
By means of the development of the supporting strut according to the invention with an absorber mass which can be axially moved inside the piston rod and can be damped by means of a liquid or gaseous medium, on the one hand, a targeted absorbing of the natural torsional frequencies of the vehicle body can be achieved and, at the same time, a compact interior unit is created which is protected from exterior influences.
The absorber mass is in each case on the end side axially slidably supported by way of spring elements, such as coil springs, and is held in an inoperative position. By means of filling the clearances receiving the spring elements with the liquid or gaseous medium, a damping of the absorber mass is achieved. In another advantageous embodiment, the medium may also consist of an electroviscous liquid which can be adjusted by means of an applied voltage, and the vibration band width can therefore be varied.
The absorber mass has a passage, such as a longitudinal bore, which connects the two clearances with one another in the hollow space of the piston rod, whereby the liquid present in these spaces, in the case of an axial movement of the absorber mass, can flow from one space into the other space.
The bearing of the absorber mass in the hollow piston rod is constructed such that the same frequency is achieved as the natural torsional frequency of the vehicle body, and thus an effective reduction of the vibrations of the vehicle body can be achieved. In particular, the absorbing effect on the natural torsional frequency of the vehicle body is generated by the fact that an additional absorbing takes place of the highenergy shock portions of the same frequency introduced from the power unit by way of the piston rod, whereby then the shocks exciting the vehicle body are largely absorbed.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.